Energy, the Carbon Cycle, and
Enduring Greenhouse Gas Management

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Knowledge of energy has allowed
humans to flourish in numbers unimaginable to our ancestors. Some are concerned
that emissions from the fossil fuels we use will lead to changing climate with
possibly disastrous consequences.

Many propose that we improve the
efficiency of energy use and conserve resources to lessen greenhouse gas
emissions and avoid climate catastrophe. It is unlikely such initiatives will
have a perceptible effect on atmospheric greenhouse gas content.

All life on earth depends on
energy and the cycling of carbon. Humans have just recently learned how to
recover fossil fuels and are recycling them by burning them in power plants,
planes, trains, and automobiles, thus modifying the carbon cycle with additional
greenhouse gas emissions.

We need to step back from micro
management of greenhouse gas emissions to more fully appreciate human influence
on the carbon cycle. Potential future human modifications to the cycle as means
to manage atmospheric greenhouse gas are considered. It is suggested humans will
need to ingeniously exploit even more energy to integrate its use with control
of atmospheric greenhouse gases.

Knowledge, especially in use of energy, has enabled our species to flourish in
numbers and with living standards unimaginable to our ancestors. Humans now
influence much of life on earth. Many are concerned that greenhouse gas
emissions from the fossil fuels we burn for energy will lead to changing climate
with disastrous consequences. Others are not so sure.

Should we finally determine there is an imperative to manage atmospheric
greenhouse gases, there are many technical solutions which may be considered. As
we seek to develop them it is imperative our strategy remain focused on the
primary goal to maintain these gases at an appropriate level.

Some organizations, for example the David Suzuki Foundation (Boyd, 2004) and the
Pembina Institute for Appropriate Development (Hornung, 1998), have provided
governments and citizens with extensive plans and advice on the resolution of
the climate change issue. Inevitably, their advice tends to focus narrowly on an
imperative to improve the efficiency of energy use and conserve resources. We
are led to believe this would lessen greenhouse gas emissions and avoid climate
catastrophe. Of course, there is still considerable scope for improving energy
efficiency. We will continue with such improvements as are achievable within the
environmental and economic constraints of sustainable development

The most optimistic outcome for a greenhouse gas management strategy based on
efficiency improvement and conservation is modest postponement of the climatic
doomsday, should it really be on the way.

We began our heavy dependence on fossil fuels some two hundred years ago. We
have been continuously improving the efficiency of the machines which deliver
useable energy - to the point some are near perfection. Improved efficiency, in
turn, encourages new applications. Our population grows, thanks to improved food
supplies resulting from efficient access to energy. Our neighbors in developing
countries recognize the benefits of energy use. They strive to emulate our
technology. Our collective greenhouse gas emissions increase enormously even as
efficiency increases. Improving energy efficiency is a commendable way to spread
energy benefits to more people now and in the future. Using fossil fuels more
efficiently has not reduced overall greenhouse gas emissions. This is not a
newly observed phenomenon. Economist William Stanley Jevon documented this kind
of response to Watt’s improvement of the steam engine in 1865. This phenomenon
of a free economic system has become known as Jevons paradox (Wikpedia).
Clearly, we need to develop a different paradigm if we are to control the
greenhouse gas content of the atmosphere.

How can we break out of this efficiency improvement trap? Perhaps we need to
step back and re-consider the role of humans and their knowledge of energy use.
Life on earth depends on energy and the cycling of carbon. Perhaps close
examination of the carbon cycle will reveal means to assist natural forms of
carbon storage outside of the atmosphere.

This paper focuses on reviewing the carbon cycle from the point of view of past
and present human influence. Some examples of potential future human input to
the cycle through science and technology to manage atmospheric greenhouse gas
are considered.

The review suggests that humans will need to ingeniously exploit even more
energy and integrate its use with control of atmospheric greenhouse gases. In
any case, continuing development and application of energy is essential if the
development of human society is to be sustained through the coming centuries.
Bold engineering initiatives to produce useable energy will continue to be
needed.

THE CARBON CYCLE

We learned early in our education that plants take carbon dioxide from the
atmosphere, lakes and oceans to manufacture their food using water and energy
from light. Plants and animals use that carbon carrying food as an energy
source. Carbon bearing material from plants and animals is incorporated into the
soil, oceans, fossil fuel and other carbon reservoirs or “sinks”. Humans have
learned how to recover fossil fuels. We are recycling them by burning them in
power plants, planes, trains, and automobiles to release carbon dioxide and
water vapor to the atmosphere. Their carbon content is thus returned to the
cycle of life. The whole complex process is driven by flows of energy. The
scientific report of the Intergovernmental Panel on Climate Change provides much
useful explanation and quantitative information on the carbon cycle. The
remainder of this section reviews and summarizes the carbon cycle based on text
and figures from the report (IPCC 2001).

The greenhouse gas “problem” is often boldly stated as “driven by fossil fuels
and land clearing”. This human activity is said to add some 8 billion tonnes of
carbon to the atmosphere annually. About 4.6 billion tonnes of this is estimated
to be absorbed by earth’s plants and oceans leaving a net accumulation in the
atmosphere of about 3.3 billion tonnes per year.

The atmosphere contains some 760 billion tonnes of carbon in the form of carbon
dioxide. Living land plants store about 500 billion tonnes of carbon in the
materials they manufacture from water and carbon dioxide as they grow. The total
store of fossil fuels is estimated at 3,000 billion tonnes of coal and 300
billion tonnes of oil and gas deposits. Earth’s complement of soil stores about
2,000 billion tonnes of carbon in materials produced by once living things.
Another 40,000 billion tonnes is dissolved in earth’s oceans. Some 100 million
billion tonnes is incorporated in sedimentary rocks such as limestone. These
massive deposits of carbon bearing materials are all considered to be products
of earth’s life over eons.

Some interesting information can be inferred from the numbers in the foregoing
paragraph. Our oil and gas deposits will last less than fifty years at current
usage rates. Coal could provide us with fuel for another 500 years. The carbon
content of the atmosphere would be doubled from its current amount in 230 years
at the current addition rate, and tripled by the time estimated fossil fuel
reserves are depleted. Of course these estimates are simplistic in the extreme.
We need to look at details of the carbon cycle.

Some 120 and 90 billion tonnes of carbon are estimated to be circulated annually
between the atmosphere and the land and oceans, respectively. Plants absorb
about 120 million tonnes of carbon from the atmosphere, as carbon dioxide, per
year. About the same amount is returned to the atmosphere by the process of
respiration of plants and animals and decay of dead organic material. The oceans
absorb and release about 90 billion tonnes with a great deal of this due to
circulation from cold to warm ocean regions. Earth’s plants use carbon dioxide
at a rate equivalent to cycling the entire carbon content of the atmosphere in
only about six years. Note that this part of the cycle is deemed, in the IPCC
science report to be “natural” even though humans manage and influence much of
the plant and animal life on earth. Perhaps this terminology is misleading. It
tends to, perhaps unduly, focus attention to the burning of fossil fuels and
land clearing as the “human perturbation” of the carbon cycle.

Life in the ocean seems to go on almost in carbon cycle isolation from that on
land – at least in the short term of a few centuries. Ocean organisms absorb
about 103 billion tonnes of carbon annually (GPP – Gross Primary Production) to
produce food. They use 58 billion tonnes themselves (autotrophic respiration) as
food and incorporate 45 billion tonnes in their structure (NPP – Net Primary
Production). Animals consume a major fraction of this and return carbon to the
water (heterotrophic respiration – 34 billion tonnes). Detritus from plants and
animals moves some carbon bearing material to deeper water. Some is diverted
through shells and dissolved material into the deep ocean. The net absorption of
some 2 billion tonnes annually from the atmosphere is thought to be a simple
result of maintaining equilibrium with the rising carbon dioxide content of the
atmosphere.

Finally, and perhaps of most importance to us, we come to the carbon cycle on
land. Details on the fate of the 120 billion tonnes of carbon absorbed annually
from the atmosphere by plants (GPP – Gross Primary Production) are of interest.
Half of this (autotrophic respiration - 60 billion tonnes carbon) is almost
immediately used by the plants themselves as food, returning carbon dioxide to
the atmosphere. That leaves 60 billion tonnes (NPP – Net Primary Production) to
be incorporated in their leaves, stems, roots, fruits and seeds. Some 55 billion
tonnes carbon content is co-opted by animals – of many sorts - and ultimately
returned to the atmosphere as carbon dioxide (heterotrophic respiration). Some 4
billion tonnes is consumed by combustion. That leaves about 1 billion tonnes to
be incorporated into soil or dissolved in water and washed down rivers to the
ocean.

Humans directly control and manage a major part of earth’s vegetation and animal
life through agriculture. We also influence the carbon cycle through our use of
forests. This review of the carbon cycle thus raises some questions. Are IPCC
figures and data subtly downplaying the role of human influence on the carbon
cycle? Is human use of fossil fuels overemphasized as the source of the problem?
Are humans involved in other major activities which influence the carbon cycle
and composition of the atmosphere? Is it possible that some aspects of the
carbon cycle, other than fossil fuel use, could be modified to play an important
role in greenhouse gas management?

HUMANS AND THE CARBON CYCLE

During the past 100 years the potential for human influence on climate has,
indeed, focused on the growth of industry driven by use of fossil fuels. Human
development of agriculture tends to be overlooked as a possible initiator of
carbon cycle and climate change. Some investigators are beginning to consider
the role of early agriculture. William Ruddiman, Professor Emeritus of
Environmental Sciences, University of Virginia is one. He considered the
possibility that the development of agriculture some ten thousand years ago
years ago may have subsequently influenced greenhouse gases and modified climate
much earlier than that attributed to the industrial age. His review (Ruddiman,
2003), suggests agriculture may have begun to alter the composition of the
atmosphere as early as eight thousand years ago.

The influence of agriculture has expanded many-fold since those early days. What
role does, or could, it play in the management of greenhouse gases? Vitousek
(Vitousek, 1986) suggests that humans appropriate about 40% of land plant
production. It was noted above that plants absorb 60 billion tonnes of carbon
annually from the atmosphere. Thus, humans control about 24 billion tonnes
annually of the carbon removed from the atmosphere by plants. That’s much more
than the 6.3 billion tonnes we added from fossil fuels in 1998 (IPCC, 2001). Is
it possible we have greater opportunities to control atmospheric greenhouse gas
levels than to simplistically reduce fossil fuel consumption? Could we take
lessons from the carbon cycle and strategically use more energy to help us
manage levels of greenhouse gases in the atmosphere?

MANAGING THE CARBON CYCLE – THE PRIMARY GOAL

Introduction

The carbon cycle itself provides much insight into methods of managing carbon
and the production and use of energy. It seems that with our already broad
involvement in Earth’s carbon cycle through agriculture, forestry and energy
science we may be able to develop the means to manage carbon bearing atmospheric
greenhouse gases. If we are to be successful, we must re-focus our attention to
the problem. We will need to concentrate our intellectual energy on maintaining
an appropriate level of greenhouse gases on the atmosphere. We will need to
integrate our energy use with other activities which influence the carbon cycle.
We may need to expand the use of energy to ensure the primary goal of managing
greenhouse gases.

Some examples of proposed technologies which directly address the primary goal
of atmospheric greenhouse gas reduction are discussed in this section. It seems
many of them will require humans to use even more energy.

Greenhouse Gas Free Energy

Let’s start with sources of energy which are deemed greenhouse gas free. Solar
energy and resultant wind energy are supplied to us on a regular basis from
fusion energy in the sun, and generate few greenhouse gases once energy
extraction systems are constructed. Wind turbines are a beautiful expression of
engineering art. Unfortunately, although the fusion energy source from the sun
is steady and reliable, the rotation of the earth and the vagaries of weather
make both solar and wind energy intermittent and unreliable. An interesting
study of a system to provide electrical energy to the United States from wind
and solar generation is available from the University of Victoria’s Institute
for Integrated Energy Systems (Love, 2003).

Nuclear energy provides another source of near greenhouse gas free energy
(Andseta, 1998) (Dones, 1998). A presentation (Van Adel, 2004) by Atomic Energy
of Canada provides an impressive photograph of two CANDU 6 reactors in China.
The beautiful earth tone of this photograph, particularly the sky and water,
reminds us of human influence on the environment. No doubt intensive agriculture
in China has contributed to the erosion of land by water. Hopefully the reactors
will help reduce the haze in the air.

Nuclear power is often somewhat simplistically touted as an alternative energy
source to avoid greenhouse gas emissions from the fossil fuel we now depend on.
It is more than that. It is a bounteous energy source which can be developed to
sustain human society far beyond that seemingly possible with dwindling fossil
fuels. Another paper (Lightfoot, 2006) in this session demonstrates the enormous
energy potential of nuclear fission. Nuclear energy can be used for an expanded
range of applications, by developing applications for the direct use of heat
and/or the production of alternate fuels such as hydrogen.

These sources of energy all have shortcomings relative to the convenience of
portable liquid fuels. Solar and wind energy also require complementary storage
to compensate for their intermittency. They are all limited to stationary
applications except for very large or very low power installations such as ships
or portable electronics, respectively. The long dreamed of development of
hydrogen technology to store and transport energy is expected to extend their
range of application and make these greenhouse gas free sources of energy more
relevant to transportation.

Interestingly, the extra processes involved in the production and use of
hydrogen will tend to reduce overall energy efficiency and tend to increase
overall energy use as we seek to switch to less greenhouse gas intensive sources
and new sources of energy to fuel our transportation systems.

Capture and Sequestration of Carbon Dioxide from Power Plants

Current fossil fuel power plants burn their fuel with air, producing an exhaust
stream of carbon dioxide, water and nitrogen which is released to the
atmosphere. Perhaps taking a clue from nature’s initiatives to sequester excess
carbon, we are considering pumping the carbon dioxide back into the ground. Some
schemes use recovered carbon dioxide to flush out additional oil and natural
gas. Others simply store it in emptied oil and gas reservoirs or in underground
saline water. Another variation contemplates burning fuel in pure oxygen to
avoid the separation from nitrogen.

Substantial new science and technology initiatives are needed to develop and
prove these concepts. It is underway. These applications will require increased
energy use for separation and pumping. Some will recover additional fossil fuel
resources.

Zero Emission Coal

Another group of energy pioneers is also taking a cue from nature’s lessons on
carbon sequestration. They propose to feed a mixture of coal, lime and water
into a chemical reactor to produce hydrogen and carbon dioxide. In an additional
step, the carbon dioxide could be combined with minerals to capture the carbon
dioxide and sequester it in the form of rock. Development work is underway
supported by governments and industry. More information can be found at the
website of ZECA Corporation (ZECA).

A proposal from the 1980’s suggested a scheme to remove carbon from the ocean
surface and deposit it deep in the ocean. More carbon dioxide could then be
dissolved at the surface. Essentially, the ocean is fertilized with iron to
increase plankton growth which would then sink. Results of a test did produce
sinking plankton. A press release (Moss Landing, 2004) suggests “billions of
tonnes of carbon dioxide could be removed from the atmosphere each year”.

Much more development work needs to be done to demonstrate the practicality of
this initiative. If it works, and we decide to control atmospheric greenhouse
gases, another new energy using industry could evolve to mine and spread iron
over the ocean simply to remove carbon dioxide from the atmosphere.

Agriculture and Forestry

Our brief review of the carbon cycle, above, indicated human agricultural
activity cycles about four times as much carbon annually as is released from
fossil fuel combustion. Science and technology have increased the productivity
of plants under our control tremendously. Irrigation, fertilizer, and plant
selection and breeding increase the annual turnover of carbon. The first two of
these are subtly integrated with energy production. Energy to supply irrigation
water is taken from potential renewable electricity production provided by the
hydrogeological cycle. Fertilizer production requires energy – and some is made
from fossil fuels. At the same time stocks of carbon in standing forests have
decreased as land is converted to food production.

Growing plants absorb carbon dioxide and incorporate it in their structure. Some
is moved into the soil by roots. Decay of plant material releases carbon dioxide
to the atmosphere. Some more durable carbon compounds tend to remain in the
soil. Large quantities have been trapped in the soil over long times. Current
agricultural practice tends to release some of it to the atmosphere by enhancing
oxidation and decay of plant derived materials.

Scientists and agricultural engineers are involved in trying to better
understand the part of the carbon cycle related to plants interaction with our
soil. No-till farming is cited as one means of capturing carbon from the
atmosphere and returning it to the soil carbon sink. Research is underway to
better manage animal wastes from intensive farming. Some promote the
preservation and extension of forests as carbon sinks.

So far the role of agriculture and forest based carbon sink management is
fraught with ambiguity. The scientific basis is uncertain. How much of the
organic material left on the land is incorporated in soil? How long will it stay
there? How much can be incorporated in soils? The basic approach to management
for potential carbon sinks is undecided. Should we account for carbon taken from
forests and built into our houses? Could carbon in lumber used to build houses
be kept from the atmosphere? How should we manage carbon bearing wastes now
going to landfills and sewers? Is it wise to dispose of carbon bearing organic
materials deemed waste in landfills or sewers? Are there better uses for these
materials which would allow humans to help control carbon dioxide in the
atmosphere?

We may ultimately harness growing plants to more effectively remove carbon
dioxide from the atmosphere and incorporate its carbon into long lasting sinks.
An emerging concept focuses on anthropogenic production and use of charcoal as a
soil amendment and carrier of fertilizer. Some charcoal, presumably from forest
and grass fires centuries ago, is found in soil demonstrating its durability.
Deposits of carbon rich black soils have been found in the Amazon (Lehmann,
2003). Archeologists are discovering evidence it was possibly man made some two
or three thousand years ago. Some scientists suggest it was deliberately
produced by a variation of slash and burn agriculture. These soils allegedly
remain highly productive long after their formation.

Interest is building in this concept. One organization (Eprida) is proposing a
process (Day, 2003) which produces charcoal based fertilizer and hydrogen fuel
from agricultural and other wastes. The raw materials include a wide range of
materials including waste wood, straw, manure, and sewage sludge. This appears
to be another opportunity to integrate energy production with greenhouse gas
management. Some sacrifice of hydrogen fuel output will be required to produce
charcoal. The Eprida website outlines the process and provides a great deal of
illustrated background information. Ongoing research and development of this
concept has potential to resolve much of the uncertainty associated with
agriculture based carbon sinks.

An earlier section indicated humans are responsible for agriculture and forestry
activity which absorbs 24 billion tonnes of carbon from the atmosphere annually.
Permanently sequestering a portion in soil could dwarf the relatively modest
emission reductions mandated by the Kyoto Protocol while re-building our soil
resource. The magnitude of the carbon sink which might be realized could
conceivably even exceed the current annual release of some 6 billion tonnes
carbon from fossil fuel. It is reasonable to speculate the associated processing
would consume considerable energy.

ENERGY, THE CARBON CYCLE AND SUSTAINED DEVELOPMENT

There are many other technical approaches to keep and/or remove greenhouse gases
from the atmosphere. There is also the possibility of modifying heat input to
the earth from the sun through other technical means (Salter, 2005). The
examples cited illustrate that many of them may increase energy use. It seems
the key to managing climate and sustaining development in the face of expanding
human population will be to think very hard about ways to expand the production
and use of energy.

Indeed, energy could be deployed to help manage the carbon cycle as suggested by
the examples in the preceding section. Water and soil may also become limiting
constraints to sustainable development. Incentives may develop to reduce the use
of water for hydroelectricity and use the energy otherwise generated to expand
irrigation and the carbon dioxide absorption capability of living plants. Other
energy sources can be developed to replace the loss of electricity. In some
areas fresh water could be pumped from regions of little use to enhance
agriculture. The use of energy for desalination has long been considered and is
done in some very dry regions which are rich in energy. Perhaps this may become
another opportunity to expand agricultural production should means of producing
copious commercial scale energy be established.

Future integration of energy supply with greenhouse gas management could come
from development of technology associated with building and enhancing earth’s
soils as suggested in the examples above. Conversion of a fraction of waste
organic materials into charcoal soil enhancements seems a promising technology
to explore as a means of coping with greenhouse gas emissions. Should this prove
workable we might even come to view greenhouse gas emissions as an asset. We
might wish we could generate more.

SUMMARY AND CONCLUSIONS

More efficient use of energy is often touted as the way to managing greenhouse
gases. Experience, over the past couple of centuries tells us increasing
efficiency of energy use simply expands applications and human population to
increase overall energy use. Since we depend mostly on fossil fuels for energy
now, there is a strong correlation between energy use and greenhouse gas
emissions. Many have come to see those emissions as a constraint to sustainable
development as they may result in damaging climate change. That possibility is
still under scientific investigation. Continuing study may eventually
convincingly demonstrate it really is a problem.
There is by no means a hard and fast correlation between energy use and
greenhouse gas emissions. There are means of producing energy, even from fossil
fuels, while controlling emissions. Technology and engineered projects can be
envisaged which will actually manage the make up of the atmosphere. Such
technology will depend on careful human use of possibly even more energy.

There are many potential constraints to sustainable development. Foremost of
these is the developing shortage of fresh water. Humans also depend on earth’s
limited stores of soil. There may come a time when humans have to restore and
build soil as a part of sustainable development. Recent observations on the
historic development of soil, driven by considerations of the potential need to
sequester carbon dioxide, point the way toward a possible solution based on
integrating our energy use with nature’s management of carbon, water and life on
earth as represented by the carbon and hydrogeological cycles.

Obviously the challenges presented by the potential need to control atmospheric
greenhouse gases are enormous. So are the opportunities. Future generations will
need to exercise their imagination to sustain development.